Since magnetic disk drives have high-capacity and are capable of fast access, they are incorporated for use in personal computers, servers and the like, and widely used as external storage devices for computer systems. Along with increased recording density, magnetic heads mounted on magnetic disk drives are needed to exhibit significantly high read/write performance. Under such circumstances, head gimbal assemblies in which a slider carrying a magnetic head element is attached to a suspension are subjected to an electrical characteristic inspection. In this inspection, head gimbal assemblies rejected because of defective magnetic head elements have been increased, resulting in a decreased production yield. If the head gimbal assemblies that have been rejected because of the defective magnetic head elements are discarded, scrap cost is increased.
To prevent the increase of the scrap cost, if the suspension itself is not damaged the magnetic head slider has been removed from the suspension for reuse of the suspension. Attachment of the magnetic head slider to the suspension is carried out by fixing the magnetic head slider to the gimbals of the suspension with an adhesive, and joining, by soldering, the pad of an electrical line formed on the gimbals with an electric terminal which is formed on the magnetic head slider and electrically connected to the magnetic head slider. The method which is currently performed to remove the magnetic head slider attached to the suspension in this way is a method of cutting the soldered portion of the magnetic head slider by a blade with the head gimbal assembly fixed to a jig. Another magnetic head slider is fixed, with an adhesive as described above, to the suspension from which the magnetic head slider has been removed by cutting the soldered portion of the magnetic head slider with the blade. Then, the pad of the electrical line on the gimbals is connected to the electrical terminal of the magnetic head slider by supplying another solder thereto. Thus, the suspension is reused.
Japanese Laid-Open Patent No. 2006-59488 (“Patent document 1”) discloses a method of removing a magnetic head slider soldered to a suspension for reuse of them by locally heating the soldered joint portion between the magnetic head slider and the suspension by laser irradiation. Patent document 1 teaches that this method eliminates heating the entire head gimbal assembly and can remove the magnetic head slider by melting solder while suppressing excessively heating the magnetic head slider or suspension. However, when a magnetic head slider is removed from a suspension, cracks occur at a solder fillet and at an electric line due to stress during cutting. Furthermore, addition of solder at the time of reusing the suspension causes a problem of reliability.
The method of cutting the soldered portion with a blade is simple because the magnetic head slider can be removed without heating the head gimbal assembly. The study by the present inventors revealed, however, that a crack due to stress encountered during the cutting occurred at the solder fillet left on the pad of the suspension. If the crack is occurring at the solder fillet left, the reuse of the suspension decreases the reliability of the joint portion; therefore, the suspension kept intact cannot be reused. Other solder may be added to the solder fillet left to connect another magnetic head slider to the suspension. This poses a problem of decreased production efficiency resulting from a reduced solder supply rate. On the other hand, it is unpreferable that the suspension be reused by removing the left solder fillet because of the increased number of man-hours. In addition, it is probable that the suspension will be damaged during removal.
While describing the method of removing a magnetic head slider soldered to a suspension, patent document 1 does not describe how to connect a magnetic had slider with the suspension when the suspension is reused. However, when another magnetic head slider is connected to the suspension by soldering, if a solder fillet is left on the suspension, there arises a problem of decreased production efficiency resulting from the reduced solder supply rate as described above.